Brian R. Searles
|October 25, 2002|
In addition, we have the following specific comments:
1. Section 1103.3 - Clear Width - It is unclear how this provision is to be coordinated with existing ADAAG minimum width of 36 inches. How is the existing guideline of providing 60 inch by 60 inch passing areas every 200 feet if less than a 60 inch passage is provided to be applied with this new clear width provision? This apparent discrepancy between two different ADAAG requirements should be clarified. It would also be helpful to clarify that this clear width should be provided across driveways, if that is the intent.
2. Section 1105.3 - Pedestrian Signal Phase Timing - The use of the slower walking speed and longer crossing distance in calculating pedestrian signal phases will certainly have an impact on overall operation of traffic signals. The guideline, as written, does not address the situation of an exclusive pedestrian phase, in which all motor vehicle traffic is stopped. If multiple crosswalks exist, which one should be used to calculate the length of the exclusive pedestrian phase? We suggest that using 3.5 feet per second and the length of the crosswalk itself (exclusive of ramps) would provide adequate crossing time for most pedestrians and would have less of an impact on overall signal operation and traffic flow.
3. Section 1105.5.3 - Approach (Pedestrian Overpasses and Underpasses) - The trigger of 60 inches in elevation change as a requirement for an elevator seems low. We suggest that 10 or 12 feet might be more appropriate triggers. Additionally, we recommend that consideration be given to the proximity of other accessible crossings (such as signalized intersections) to overpasses and underpasses. For example, if an accessible pedestrian signal is located no more than 300 feet (consistent with draft AASHTO guide for design of pedestrian facilities) from an overpass, then no elevator would be required.
4. Section 1105.6.1 - Separation (at roundabouts) - As written, it is not clear what portion of the roundabout is considered as having "prohibited" pedestrian crossings. Would this be the area between marked crosswalks? Would any of the approach leading up to a marked crosswalk be included in the "prohibited" area? If visually impaired pedestrians generally use curbs to discern where it is unsafe to cross, why would roundabouts be treated differently than other intersections? Assuming that the circular nature of roundabouts is confusing to those with visual disabilities, maybe other technologies like audible messages could be used to clarify where marked crosswalks are and what type of intersection treatment is present.
5. Section 1105.6.2 - Signals (at roundabouts) - The requirement for signals at roundabout crosswalks will negate many of the traffic flow and traffic calming benefits that roundabouts offer over traditional signalized intersections.
6. Section 1105.7 - Turn Lanes at Intersections - The requirement for signals at all crosswalks that cross slip lanes will have significant impacts on overall traffic flow, in addition to significant cost increases.
7. Section 1106.3.4 - Optional Features (of pedestrian pushbuttons) - It is unclear what additional features could be activated by pedestrian pushbuttons. A listing of these potential features would be helpful.
8. Section 1111.3 - Location (of alternate circulation path) - It is proscriptive to state that the alternate route must be on the same side of the street as the closed sidewalk. It may be more helpful to state that the preferred route is the same side of the street, unless it is unsafe to do so, in which case nearby parallel routes may be provided.
We appreciate the opportunity to comment on the draft guidelines. Please do
not hesitate to contact me if you have any questions or require additional
Brian R. Searles
Secretary of Transportation
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